The radio interface of the W-CDMA (Wideband Code Division Multiple Access) scheme, which is adopted as the radio access scheme of the third-generation mobile communication system, is extended, and for the purpose of further increasing the speed, HSDPA (High-Speed Downlink Packet Access) and HSUPA (High-Speed Uplink Packet Access) have been studied and specified. As a successor to the systems, for the purpose of further increasing frequency usage efficiency and peak data rates, reducing connection delay and the like, the Long-Term Evolution (LTE) system of the current system has been studied and specified in 3GPP (3rd Generation partnership Project) that is a standardization group of W-CDMA (Non-patent Document 1). In LTE, as distinct from W-CDMA, as radio access schemes, the scheme based on OFDMA (Orthogonal Frequency Division Multiple Access) is adopted in downlink, and the scheme based on SC-FDMA (Single Carrier Frequency Division Multiple Access) is adopted in uplink.
OFDMA is a multicarrier transmission scheme for dividing a transmission frequency band into a plurality of narrow frequency bands (subcarriers) and mapping data to each subcarrier to perform transmission. The multicarrier scheme is high in tolerance to frequency selective fading (multipath interference) such that the effect becomes remarkable by broadening the band, and therefore, holds promise of providing signal transmission with higher quality than the single-carrier transmission scheme.
SC-FDMA is of single-carrier transmission, is thereby low in the temporal variation (Peak to Average Power Ratio) of transmission power, and is preferable from the viewpoints of expansion of coverage and low power consumption in the terminal. Further, as distinct from W-CDMA, SC-FDMA is a single-carrier transmission scheme for transmitting (frequency division multiplexing) data from different users using respective different frequency bands in some transmission interval.
In LTE, to improve efficiency in the use of radio resources more than the present time, radio resources using both the frequency domain and time domain are allocated to each user apparatus. The radio resources are allocated us ing a block of a size comprised of some band (for example, 180 kHz) and some transmission interval (for example, 1 msec) as a unit. This unit is called the resource block (RB). In relation to the frequency and time domains, by instantaneously allocating one or more resource blocks to users in the channel state, it is possible to enhance entire system throughput. Allocation of resource blocks to users is determined in a base station, and the processing is called scheduling.
As distinct from the 3G mobile communication system optimized for circuit-switching networks, LTE is optimized for packet-switching networks. Meanwhile, in LTE, at least voice data (VoIP) needs to achieve good radio quality equal to voice transmission using circuit-switching networks. Therefore, in LTE, circuit-switching like radio resource allocation is performed on voice data. More specifically, a certain pattern of radio resources is allocated to voice data periodically (at fixed time intervals), and radio resources are thereby allocated more preferentially than data communications.
As shown in FIG. 1, signals transmitted in uplink are mapped to appropriate radio resources, and transmitted from a mobile terminal apparatus to a radio base station apparatus. In this case, user data (user data from user equipment (UE) #1 and UE #2) is allocated to the PUSCH (Physical Uplink Shared Channel), and control information is time-multiplexed with a data signal on the PUSCH when the control information and user data is concurrently transmitted, while being allocated to the PUCCH (Physical Uplink Control Channel) when only the control information is transmitted. As shown in FIG. 1, the PUCCH is multiplexed into radio resources each having a narrow frequency bandwidth at opposite ends of the system band, inter-slot frequency hopping (Inter-slot FH) is applied to two slots having different frequency bands in a subframe, and it is configured to obtain high frequency diversity gain.
The transmission bandwidth of the PUSCH is determined by instructions of the radio base station apparatus (frequency scheduling), and typically, more information symbols are transmitted on the PUSCH than on the PUCCH with the narrow band. As shown in FIG. 2, a subframe of the PUSCH is comprised of two slots, and one slot is comprised of seven SC-FDMA symbols. A reference signal (RS) used in channel estimation for coherent detection demodulation of data is multiplexed into the fourth symbol in a slot, and data and control information is multiplexed into the other symbols (first symbol (#1) to third symbol (#3), fifth symbol (#4) and seventh symbol (#6)). In addition, in one subframe, the slot is repeated twice. As in the PUCCH, it is also possible to apply inter-slot frequency hopping.